1. Field of the Invention
The present invention relates to a recording apparatus adapted for recording information signals in different areas of a recording medium.
Description of the Related Art
Throughout the specification, the recording apparatus will be described, by way of example, as being a multi-channel digital audio tape recorder in which audio signals which are compressed in terms of time axis are modulated and recorded independently in 6 channels which extend in the longitudinal direction of a magnetic tape by means of rotary heads.
FIG. 1 shows a part of a tape running system which is used in this type of digital audio tape recorder. In FIG. 1, reference numerial 1 denotes a magnetic tape, 2 denotes a rotary cylinder, and 3 and 4 denote rotary heads carried by the rotary cylinder 2. As the rotary cylinder 2 rotates, each of the heads 3 and 4 obliquely traces the tape 1 so as to record audio digital signals. The arrangement is such that audio signals compressed in terms of time axis are recorded in six areas extending along the length of the tape 1, for each 36.degree. rotation of the heads 3,4, thus realizing an audio tape recorder capable of recording six-channel audio signals.
Referring now to FIG. 2, while the head 3 or 4 traces the regions A-B, B-C, C-D, D-E, E-F and F-G, audio signals are recorded in areas or channels CH1 to CH6. Each channel is capable of recording the audio signal independently, and so-called azimuth duplicating writing is effected. However, it is not necessary that the channels CH1 to CH6 are on a common straight line. A pilot signal is recorded in each channel for the purpose of tracking control. The recording of pilot signal is conducted in each region in a predetermined rotation (f.sub.1 .fwdarw.f.sub.2 .fwdarw.f.sub.3 .fwdarw.f.sub.4). There is no need for specific correlation between channels also in regard to the recording of pilot signals.
It is assumed here that recording or reproduction in and from the channels CH1 to CH3 is conducted while the tape 1 is running in the direction of arrow 7 in FIG. 1, while the recording or reproduction in and from the channels CH4 to CH6 is conducted while the tape is running in the direction of arrow 9 in FIG. 1. In such a case, as shown in FIG. 2, the degree of inclination of the tracks in the channels CH1 to CH3 and that of the tracks in the channels CH4 to CH6 are somewhat different from each other. However, the difference in the relative speed caused by the running of the tape 1 is extremely small as compared with that caused by the rotation of the heads 3 and 4 and, therefore, is considered as being negligible.
FIG. 3 is a time chart of the recording and reproducing operation performed by the tape recorder explained in connection with FIGS. 1 and 2. In FIG. 3, (a) represents phase detecting pulse (referred to as "PG(a)", hereinafter) which is switched between high level (H) and low level (L) for each 1/60 second. Thus, the phase detecting pulse PG is a rectangular wave pulse having a frequency of 30Hz. On the other hand, (b) represents PG (referred to as "PG(b)" hereinafter) which has a polarity inverse to that of PG(a). It is assumed here that PG(a) takes the H level while the head 3 rotates from the point B to the point G in FIG. 1, while PG(b) takes a low level while the head 4 rotates from the point B to the point G.
In FIG. 3, (c) represents data reading pulses which are derived from PG(a). Audio signals corresponding to the period corresponding to one field (1/60 second) of video signal are sampled for every other field when this pulse takes high level H. The signal represented by (d) in FIG. 3, when it takes the high level H, conducts various signal processings such as addition of a redundant code for error correction by means of a RAM, for example, to the sampled one-field audio data, or rearrangement of the audio data. The data to be recorded, obtained through the signal processing explained above, is recorded in the tape 1 in the periods in which a signal shown at (e) in FIG. 3 takes high level H.
The flow of signal in relation to time will be explained with reference to FIG. 3. The data signal sampled in the period between the moments t1 and t3 in which the head 3 moves from the point B to the point G is processed in the period between the moments t3 and t5 in which the head 3 moves from the point G to the point A, and is recorded in the period between the moments t5 and t6 in which the head 3 moves from the point A to the point B. Namely, the data signal is recorded in the channel CH1 by the head 3. On the other hand, the data signal sampled in the period in which PG(b) takes the high level is processed in the similar timing and is recorded in the channel CH1 by the head 4.
In FIG. 3, (f) shows PG (referred to as "PG(f)" hereinafter) which is obtained by shifting PG(a) by a predetermined phase amount which is, in this case, 36.degree. amounting to one channel.
An explanation will be given hereinunder as to the manner in which the audio signal is recorded by PG(f) and a PG (not shown) which has a polarity reverse to that of PG(f). Referring to FIG. 3, the data signal sampled in the period between the moments t2 and t4 is processed in the period between the moment t4 and t6, in accordance with a signal shown at (g) in FIG. 3, and is recorded in the period between the moments t6 and t7 in accordance with a signal shown at (h) in FIG. 3. Namely, the recording is conducted by the head 3 in the channel CH2 shown in FIG. 2, during the period in which the head 3 traces the region between B and C. Similarly, the data signal sampled in the period between the moments t4 and t7 is recorded in the channel CH2 by means of the head 4.
A description will be made hereinunder as to the operation for reproducing the signal recorded in the channel CH2.
The reading of the data from the tape 1 by the head 3 is conducted in the period between the moment t6 and t7, as well as in the period between the moments t1 and t2, in accordance with the signal shown at (h) in FIG. 3. Then, a signal processing which is reverse to that conducted during recording is performed in accordance with a signal shown at (i) in FIG. 3, in the period between the moments t7 and t8, as well as in the period between the moments t2 and t3. Namely, an operation including the error correction is conducted in these periods, and the reproduced audio signal is output in the periods between the moments t8 and t9 and between the moments t3 and t6, in accordance with the signal which is shown at (j) in FIG. 3. Meanwhile, reproducing operation by the head 4 is conducted at 180.degree. phase interval with respect to the reproducing operation performed by the head 3, so that a continuous reproduction of audio signal is performed.
Needless to say, the recording and reproducing operations explained above are conducted also with the channels CH3 to CH6, through n.times.36.degree. phase shifts of PG(a). It is to be noted also that the recording and reproducing operations have no dependency on the direction of running of the tape.
An explanation will be given hereinunder as to an example of data formatting operation which has been conventionally used in the recording and reproducing apparatus of the kind described. FIG. 4 shows an example of the data format containing PCM audio data corresponding to audio signals of two channels of 1/60 seconds, which data format is recorded in each track of each channel in FIG. 2.
A data matrix shown in FIG. 4, has synchronizing data columns SYNC, address data columns ADDRESS, error correction redundant data columns P and Q, check code data columns CRCC known per se, and data columns D1, D2 each having a plurality of rows and each containing 2-channel audio information signal. The data matrix also has lines b(o) to b(3x-1). The arrangement is such that each line constitutes a data block. Data blocks thus formed are successively recorded such that the recording is commenced first with the leftmost data block and then the right blocks are successively recorded. For instance, the data in the ADDRESS column of the line b(o) is recorded subsequently to the recording of the SYNC data, and then the data in the column P of the line b(o) is recorded. Similarly, the data in the SYNC column of b(e+1) is recorded subsequently to the recording of the data in the final column of the line b(e). Thus, the recording of data contained in one track is completed when the data in the final column of the line b(3x-1) is finished.
The six data in the first one of the rows contained by the data column D1 in the lines b(0), b(1), b(x), b(x+1), b(2 x) and b(2x+1), i.e., the data ID0 to ID5, are the data corresponding to added information other than the audio signals, and will be generally referred to as "ID data", hereinafter.
In general, a multi-channel digital audio tape recorder of the type described functions to enable the channels to be changed during recording or reproduction. Such a function is very important because it enables the recording time to be prolonged. In order that such a function is successfully performed, it is necessary that the data such as the position on the track at which the recording is finished before the changing of the channel, the number of the new channel, i.e., the channel to which the recording operation is to be changed, signal recording direction in the new channel, the point at which the recording is commenced, and the speed of running of the tape are recorded in the old channel, i.e., the channel from which the recording operation is to be changed-over to the new channel.
The tape recorder of this type is usable also as a VTR, as is well known. In order to enable the discrimination between the video signal and the audio signal, therefore, it has been a common measure to superpose, only on the digital audio signal, a pilot signal having a frequency f.sub.5 which is different from four kinds of pilot signal used in known 4-frequency type tracking control.
FIG. 5 shows the frequencies of these pilot signals, while FIG. 6 shows a detecting circuit for detecting the pilot signal f.sub.5.
Referring first to FIG. 6, the synthetic signal reproduced by the head 30 is amplified by a head amplifier, and the amplified signal is made to pass through a band-pass filter (BPF) 32 which has the central frequency equal to the frequency f.sub.5 of the pilot signal, so that only the signal component of the frequency f.sub.5 is extracted. This signal is sent to a detector (DET) 33 for level detection. When the level is higher than a reference voltage V.sub.ref, a comparator 34 outputs high level H of binary signal.
When the signal of the frequency f.sub.5 is detected during reproduction or searching in one of six channels, it is decided that the channel from which the signal of the frequency f.sub.5 is detected is the channel in which the audio signal has been recorded.
In the conventional apparatus, the signal of the frequency f.sub.5 enables only the confirmation of the fact that the recording of the multi-channel digital audio signal has been completed. The searching through recording programs, however, is extremely difficult to conduct if the search is to be conducted only by means of the confirmation of the presence of the digital audio signal, considering that the number of the channels is as large as six.
It is, therefore, desirable that the information concerning the change-over between the channels be written as ID data during the recording.
FIGS. 7(a) and 7(b) show an example of the setting pattern for setting the manner in which six programs are automatically recorded by using devices such as a timer device.
It is conceiveable that 6 channels are used in such a manner that each channel has one program, as shown in FIG. 7(a). This pattern will be referred to as "parallel setting pattern" hereinafter. In another pattern which will be referred to as "series setting pattern", all the programs are handled in series in such a manner that the first channel contains the programs as much as possible starting with the first program. If the first channel is filled up, the overflow of the programs are stored in the second channel and any overflow is contained in the third channel. In this manner, the series of programs down to the sixth program is stored.
These setting patterns are only illustrative, and other setting patterns can be used equally well. All these setting patterns, however, encounter the following problem. Namely, it is generally difficult to detect, when change-over of the channels has been conducted in a multi-channel recording and reproducing apparatus, the point on the old channel at which the recording was ceased and the point on the new channel at which the recording was commenced. This problem can be overcome by providing data concerning the change-over of the channel in the ID data area.
However, the writing of the channel change-over data in the ID data area in the conventional apparatus requires a specific manual operation. In fact, it is quite difficult to record the data concerning the change-over of the channels during automatic recording conducted by means of a timer device.
When conducting an automatic recording by means of a timer device, a problem is encountered as to the necessity for the judgment concerning the allocation of the programs to the tracks, i.e., as to which one or ones of the tracks the program is to be recorded.
Another problem is that, when a plurality of programs including programs of video signal and the recording programs having only audio signals are to be recorded by means of a timer, it is not possible to attain a high rate of utilization of the tape, if the selection of channels is conducted by a mere time-shifting type method. In order to enable the tape to be fully used, a complicated control is necessary for the purpose of setting of the recording positions. Summary of the Invention:
Accordingly, an object of the present invention is to provide a multi-channel recording apparatus capable of overcoming the above-described problems of the prior art.
Another object of the present invention is to provide a multi-channel recording apparatus which is suitable for use in automatic recording by means of a timer device.
Still another object of the present invention is to provide a multi-channel recording apparatus which is easy to operate and which facilitates searching of recorded information.
To these ends, according to the present invention, there is provided an information signal recording apparatus comprising: recording means capable of recording pieces of information in a plurality of channels on a recording medium; setting means for setting the time of completion of recording and the channel of recording for each of first and second programs to be recorded; memory means for storing, for each of the first and second programs, first information pertaining to the recording channel and second information pertaining to the time of completion of recording; selecting means for selecting, out of the plurality of channels, the channels in which the information signal is to be recorded by the recording means, the selecting means being adapted to select, in accordance with the first information, the channels in which the information signals concerning the first and second programs are to be recorded; and causing means for causing, when the recording means is recording the information signal pertaining to the first program, the recording means to record, together with the information signal, said first information pertaining to the second program stored in the memory means in accordance with the second information pertaining to the first program.
A further object of the present invention is to provide a multi-channel recording apparatus which enables a recording medium such as a tape to be fully used.
To this end, the present invention provides an information signal recording apparatus comprising: recording means capable of recording pieces of information in a plurality of channels which are provided in a parallel fashion on a recording medium so as to extend in the longitudinal direction of the recording medium; first setting means for setting the time of start of recording and the time of completion of recording for each of a plurality of programs including a program pertaining to first information which is to be recorded by said recording means in only one of the plurality of channels and a program pertaining to information which is to be recorded over at least two of the plurality of channels; and second setting means for setting the position of recording of the program pertaining to the second information in advance of the setting of the position of recording of the program pertaining to the first information.
Other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiments taken in conjunction with the accompanying drawings.